The games in the series have been praised as being among the best first-person shooters on a video game console, and are considered the Xbox's "killer app".[5] This led to the term "Halo killer" being used to describe console games that aspire, or are considered, to be better than Halo.[6] Fueled by the success of Halo: Combat Evolved, and by immense marketing campaigns from publisher Microsoft, its sequels went on to record-breaking sales.[7][8][9] The games have sold over 65 million copies worldwide, with the games alone grossing almost $3.4 billion.[10][11][12]

In the distant past, a powerful race called the Forerunners fought an alien parasite known as the Flood. The Flood, which spread through infestation of sentient life, overran much of the Milky Way Galaxy. One of the races affected was humanity, who came into conflict with the Forerunners as a result. Exhausted by their war and after having explored all other options, the Forerunners conceived a weapon of last resort to combat the Flood, called the Halo Array. Using an installation known as the Ark, they built large ring-shaped megastructures known as Halos. The Halo Array, when activated, would destroy all sentient life in the galaxy – depriving the Flood of their food, after which samples of the lost lifeforms would be reseeded. Delaying as long as they could, the Forerunners activated the rings and disappeared.[15] Tens of thousands of years later, in the 26th century, humanity – under the auspices of the United Nations Space Command, or UNSC – colonize many worlds thanks to the development of faster-than-light "slipspace" travel. Tensions escalate between the older and more stable "Inner Colonies" and the remote "Outer Colonies", leading to civil war. The UNSC sponsors the Spartan-II program to create an elite group of enhanced supersoldiers, whose purpose is to suppress the rebellion covertly.[16] In the year 2525, human worlds come under attack by a theocratic alliance of alien races known as the Covenant. The Covenant leadership declares humanity heretics and an affront to their gods – the Forerunners – and begins a holy war of genocide. The Covenant's superior technology and numbers prove decisive advantages; though effective, the Spartans are too few in number to turn the tide of battle in humanity's favor.

In 2552, the Covenant arrive at the UNSC's last major stronghold beyond Earth – the planet Reach, in orbit of Epsilon Eridani – and launch an invasion of the planet. The last Spartans and UNSC military are unable to stop the Covenant from bombarding the planet. The UNSC Navy suffers devastating losses, and every Spartan but their leader, player characterMaster Chief John-117, is believed lost in action. Following directives to avoid leading the Covenant to Earth, Cortana, the AI aboard the fleeing UNSC ship Pillar of Autumn, selects random coordinates that lead the ship to a Halo installation. These events form the backdrop to the first game in the series, Halo: Combat Evolved.

Over the course of the game, the Covenant pursue, damaging the Autumn and leading its crew to wage a guerrilla war on the ring's surface. The Covenant accidentally release Flood imprisoned on the ring; to nullify the threat, the ring's AI caretaker, 343 Guilty Spark, enlists the help of the Master Chief in activating Halo. Cortana reveals that Halo's activation would mean their own destruction. Master Chief and Cortana instead detonate Autumn's engines, destroying Halo and preventing the escape of the Flood.

Between the events of the first game and Halo 2, the Chief and a few other survivors return to Earth, warning of an impending Covenant attack; this attack forms the first mission of the game. Meanwhile, the Covenant, unaware of the destructive nature of the rings, attempt to fire another ring, Installation 05, to fulfill their religious prophecy[17] and to do so launch an attack on Earth. Helping the Chief to defend the Earth are Sergeant Avery Johnson and Commander Miranda Keyes. One race in the Covenant, the Elites, learn the truth about the rings and are led by a former Elite commander named the Arbiter (also a player character) to join forces with humanity to stop the firing of the ring. Though they are successful, the unexpected shutdown of the installation triggers a fail-safe protocol, priming all the rings for firing from the Ark.[18]

Halo 3 picks up immediately after, with the Covenant's leader, the High Prophet of Truth, and the remaining loyalist Covenant uncovering a portal to the Ark on Earth. A battle rages on Earth between human forces, the Covenant, and a Flood-infected army. Eventually, the Covenant is repulsed and flees through a slipspace portal, and the Flood is purged from Earth, though much of Africa has been devastated in the battle.

Chief, Arbiter, Elites, Johnson, Keyes, and U.N.S.C. troops follow Truth through the portal, joined by 343 Guilty Spark, who aids the Chief as he has no function to fulfill after the destruction of his ringworld. During the ensuing battle between humans, Covenant, and the Flood on the Ark, Johnson is captured by Truth to activate the Halo rings. Keyes tries to intervene, but is killed. Master Chief and the Arbiter, aided by the Flood, kill the Covenant "Prophet of Truth" and rescue Johnson. After finding out that the Ark is constructing a replacement for Guilty Spark's Halo installation, Master Chief decides to fire the unstable Halo, destroying both the Flood and the Ark. After finding out about their plan, Guilty Spark kills Johnson and tries to kill Master Chief, but Master Chief destroys Guilty Spark and activates the Halo. Master Chief and the Arbiter escape on the UNSC frigate Forward Unto Dawn, but the slipspace portal closes with Master Chief's half trapped in space. After a memorial service on Earth for the victims of the Human-Covenant war, the Arbiter and his Elite brethren depart for their home planet. The rear half of Forward Unto Dawn floats in deep space. Cortana activates a distress beacon and the Chief goes into hibernation.

Four years later, the Chief and Cortana awake to find they are being attacked by a Covenant splinter group (Halo 4). Caught in an artificial gravity well, they are pulled into the artificial Forerunner planet of Requiem, along with the UNSC ship Infinity.[19][20] Master Chief, fighting Covenant and AI soldiers called Prometheans, unwittingly releases a hostile Forerunner warrior called the Didact. While seeking a way to combat the Didact, Cortana reveals that she is becoming "rampant" (an inevitable state leading to insanity that AIs reach when their knowledge base finally becomes too large). Master Chief is eventually contacted by a Forerunner consciousness called the Librarian (The Didact's Wife), who tells him about the Didact: during the crisis with the Flood, the Didact tried to use a device called the Composer to transform humanity into creatures like the Prometheans. He did this because he needed extra soldiers in the war. His own race then imprisoned him along with Forerunner soldiers and humans he had already converted. The Composer was hidden. After the Didact leaves Requiem and retrieves the Composer, Master Chief pursues him to Earth, with Master Chief and Cortana working together to destroy the Composer. Master Chief succeeds, but Cortana sacrifices herself to save him from the resultant explosion. Master Chief is later found floating among the rubble, and taken back to Infinity.

Halo 5: Guardians begins eight months later. Blue Team — consisting of four of the five remaining Spartans (Master Chief, Fred-104, Kelly-87 and Linda-58), receives signals from Cortana indicating that she has survived her death by taking advantage of Forerunner AI technology. The Chief, disobeying direct orders, travels to the planet Genesis to reunite with her. A team of Spartans from a competing program, Fireteam Osiris, are dispatched to apprehend him. This journey takes them to several places around the galaxy, including the Elite homeworld of Sanghelios, where the Arbiter leads an offensive against the final remnants of the loyalist Covenant. As they travel, Osiris discover that Cortana is activating ancient Forerunner constructs — the eponymous Guardians — with which she plans to impose permanent galactic peace on pain of death. She holds the Master Chief's team captive, and while Fireteam Osiris are able to rescue them, they are not able to stop Cortana from executing her plan, disabling most contemporary technology and bringing all remaining sentient species under her aegis. As the game ends, Blue Team, Fireteam Osiris and the Arbiter regroup to plan their resistance.

The games of the main Halo trilogy were developed by Bungie, and are first-person shooters in which the player experiences most action from the protagonist's perspective.[21] The first title in the series is the Xbox version of Halo: Combat Evolved, released on November 15, 2001.[22] The game was initially intended to be released for Windows and Mac OS, until Microsoft's purchase of Bungie in 2000 led to the game becoming an Xbox launch title and delaying any release for personal computers for 2 years.[23][24]Halo: Combat Evolved introduced many gameplay and plot themes common to the whole trilogy. Players battle various aliens on foot and in vehicles to complete objectives, while attempting to uncover the secrets of the eponymous Halo. One concept introduced in Halo: Combat Evolved, is limiting the number of weapons players could carry to two, forcing them to carefully select their preferred armament.[25] Players fight with ranged and melee attacks, as well as a limited number of grenades. Bungie refers to the "weapons-grenades-melee" format as the "Golden Triangle of Halo",[26] which has remained fundamentally unchanged throughout the trilogy. In Halo: Combat Evolved, the player's health is measured in both hit points and a continually recharging energy shield; the sequels forgo the hit point system, although it returns in spin-offs.[27] A Windows and Mac OS Xport was later developed by Gearbox Software, and released on September 30 and November 11, 2003, respectively.[28][29] A stand-alone expansion, entitled Halo: Custom Edition, was released as a Windows exclusive, and allowed players to create custom content for the game.

Its sequel, Halo 2 was released on the Xbox on November 9, 2004, and later for Windows Vista on May 17, 2007. For the first time, the game was released in two different editions: a standard edition with just the game disc and traditional Xbox packaging; and the Collector's Edition with a specially designed aluminum case, along with an additional bonus DVD, extra booklet, and slightly different user manual. Halo 2 introduced new gameplay elements, chief among them the ability to hold and fire two weapons simultaneously, known as "dual wielding".[30] Unlike its predecessor, Halo 2 fully supported online multiplayer via Xbox Live. The game uses "matchmaking" to facilitate joining online matches by grouping players looking for certain types of games.[30] This was a change from the more traditional "server list" approach, which was used to find matches in online games at this time. Upon release, Halo 2 became the game played by the most people on the Xbox Live service that week; it retained this title for over two years – the longest streak any game has held the spot.[31]

Halo 3 is the final game in the main Halo trilogy, ending the story arc begun in Halo: Combat Evolved.[32] The game was released on the Xbox 360 on September 25, 2007.[33] It adds to the series new vehicles, new weapons, and a class of items called equipment.[34] The game also includes a limited map-editing tool, known as the Forge, which allows players to insert game objects, such as weapons and crates, into existing multiplayer map geometry.[35] Players can also save a recording of their gameplay sessions, and view them as video, from any angle.[36]

At E3 2014, Microsoft and 343 Industries announced Halo: The Master Chief Collection, released on November 11, 2014, for the Xbox One. The game includes the full campaign and multiplayer modes of Halo: Combat Evolved, Halo 2, Halo 3, and Halo 4. The campaign of Halo 3: ODST was later released as DLC, and was free for those who bought The Master Chief Collection during late 2014.

Following Bungie's split from Microsoft, 343 Industries – a studio established by Microsoft in 2009 – took the helm of the Halo franchise.[37][38][39] 343 had already co-developed the Halo Legends animated series and had overseen production of Halo: Reach and Halo: Combat Evolved Anniversary.[40] The next game in the series, Halo 4, was announced at E3 2011 as the first entry in what would be a new series of Halo games, also known as the "Reclaimer Trilogy".[41][42] The game included many staples of previous games, such as new or redesigned weapon types,[43] an improved map-editing tool[44] and expanded multiplayer options and maps.[45]Halo 4 was released worldwide on November 6, 2012,[46] achieving record sales for the franchise.[47] In a new addition to the series, a story-driven multiplayer campaign entitled Spartan Ops was released over the weeks following Halo 4's release, telling what happened after the end of the main game.[48]

Halo 5: Guardians, the sequel to Halo 4, was released for the Xbox One on October 27, 2015.[49] The game takes place on many different worlds, mainly the Covenant's, and revolves around Spartan Locke's hunt of Master Chief.[citation needed]

The success of the main Halo trilogy spurred the creation of spin-off games. Halo Wars is a real-time strategy game developed by Ensemble Studios for the Xbox 360. Set in the year 2531, the game takes place 21 years prior to the events of Halo: Combat Evolved. Much effort was spent on developing a control scheme that was simple and intuitive, unlike other console strategy games.[50] The game was announced at X06, and released in February and March 2009.

In a July 2008 interview with MTV, Microsoft's head of Xbox business, Don Mattrick, stated that Bungie was working on a new Halo game for Microsoft, independent of other Halo projects. An announcement of the new Halo project was expected at the 2008 E3 game exposition, which Bungie stated "has been building for several months", but was delayed by their publisher Microsoft.[51] The Halo announcement was to be part of Microsoft's 150-minute E3 presentation, and was cut to trim the presentation down to 90 minutes; Microsoft stated it wanted to give the game its own dedicated event.[52] After the release of an ambiguous teaser trailer on September 25,[53] the project was revealed as Halo 3: Recon, later changed to Halo 3: ODST. Set between the events of Halo 2 and Halo 3, players take control of elite human soldiers called Orbital Drop Shock Troopers (ODST). The game was released on September 22, 2009.

Announced at E3 2009, Halo: Reach is a prequel to the main trilogy and Bungie's last Halo game. Players control Noble Six, a "Hyper Lethal Vector" who is one of the members of the Spartan squad "Noble Team" as they defend Reach against the Covenant. The ending of the game leads directly into the events of Combat Evolved. The game was released on September 14, 2010.

Alternate reality games were used to promote the release of the games in the main trilogy. The Cortana Letters, a series of cryptic email messages, were circulated by Bungie prior to Halo: Combat Evolved's release.[54]I Love Bees was used to promote the release of Halo 2. The game revolved around a website created by 42 Entertainment, commissioned by Microsoft and endorsed by Bungie. Over the course of the game, audio clips were released that eventually formed a complete five-hour story set on Earth between Halo and Halo 2.[55][56] Similarly, Iris was used as a viral marketing campaign for the release of Halo 3.[57] It featured five web servers containing various media files related to the Halo universe.

Spin-off titles were planned for release on handheld systems, but did not progress far in development. Rumors of a handheld Halo title for the Game Boy Advance surfaced in 2004. Bungie denied the rumors and commented that such a project between Microsoft and Nintendo would be "very unlikely".[58] At a Las Vegas consumer technology convention in January 2005, rumors spread about a version of Halo for the handheld Gizmondo system. Bungie denied the rumors stating they were not making a game for the system.[59] A former Gizmondo employee later revealed development only extended to basic story and game structure concepts to obtain funding from investors.[60] In 2006, a concept video for Microsoft's portable Ultra-Mobile PC featured footage of Halo and caused speculation for a handheld title. Microsoft later stated the footage was for demonstration purposes only; Halo was included because it was a Microsoft-owned property.[61] In January 2007, IGN editor-in-chief Matt Casamassina claimed he played a version of Halo for the Nintendo DS.[62] He later demonstrated on-camera, in-game footage of an early-development style version of Halo DS.[63] The demonstrated work featured dual-wielding and a version of the Halo 2 map Zanzibar.[62] On October 5, 2007, Bungie employee Brian Jarrard explained the Halo DS demo was in fact an unsolicited pitch that was never taken on.[64]

In 2006, Microsoft announced an episodic video game to be developed by film director Peter Jackson's Wingnut Interactive.[65] The game, dubbed Halo: Chronicles, was confirmed to be in development in 2007,[66] and by 2008 was still hiring for positions on the development team.[67] Jackson told game blog Joystiq in July 2009 that the project was no longer in development.[68][69] Jackson's manager Ken Kamins explained that the project was cancelled as part of budget cuts tied to job layoffs in January 2009.[70]

Before the company was shuttered after producing Halo Wars, Ensemble Studios had been working on a Halo-themed massively multiplayer online game, often referred to as Titan Project, or just Titan. The project was cancelled internally in 2007–2008, without a formal announcement from Microsoft.[71][72]

On March 25, 2015, 343 Industries announced Halo Online, a free-to-playHalo multiplayer game for Windows. A closed beta test limited to Russia launched in the second quarter of 2015. The title was developed with Saber Interactive and published by Innova Systems; it is powered by a modified version of the Halo 3 engine.[76] The project was cancelled in August 2016.[77]

In December 2014, 343 Industries general manager Bonnie Ross expressed Microsoft's aim for the Halo series to last at least 30 more years.[78] Furthermore, at Gamescom 2015 Microsoft announced a sequel to Ensemble's Halo Wars, Halo Wars 2, slated to launch in February 2017. The game is being developed by 343 Industries and Creative Assembly.

Bungie (formerly Bungie Software Products Corporation) is a game development company started in 1991 by Alex Seropian. Seropian partnered with programmer Jason Jones to market and release Jones' game Minotaur: The Labyrinths of Crete. Focusing on the Macintosh game market because it was smaller and easier to compete, Bungie became the biggest Mac developer with games including the shooters Pathways into Darkness and Marathon. What became Halo was originally code-named Monkey Nuts and Blam!,[79] and took place on a hollowed-out world called Solipsis.[80] The planet eventually became a ringworld, and an artist suggested the name "Halo", which became the game's title.[81]

The first Halo game was announced on July 21, 1999, during the Macworld Conference & Expo.[82] It was originally planned to be a real-time strategy game for the Mac and Windows operating systems, but later changed into a third-person action game.[23][82][83] On June 19, 2000, Microsoft acquired Bungie Studios and Halo: Combat Evolved became a launch title for the Xbox video game console.[24] After receiving Xbox development kits, Bungie Studios rewrote the game's engine, heavily altered its presentation, and turned it into a first-person shooter. Though the first Halo was meant to include an online multiplayer mode, it was excluded because Xbox Live was not yet available.[84]

Halo was not intended to be the Xbox's flagship game due to internal concerns and gaming press criticism, but Microsoft VP of game publishing Ed Fries did not act on these concerns. The Xbox's marketing heavily featured Halo, whose green color palette meshed with the console's design scheme.[85]

The success of the game led to a sequel, Halo 2, which was announced on August 8, 2002, at Microsoft's New York CityX02 press event.[86] It featured improved graphics, new weapons, and a multiplayer mode on Xbox Live.[87][88]Halo 3 was announced at the 2006 Electronic Entertainment Expo.[89] The initial conception for the third game was done before Halo 2 was released in 2004.[90] It utilized a proprietary, in-house graphics engine, and employed advanced graphics technologies.[91][92]

They created two more Halo games before becoming independent as part of their deal with Microsoft: a side story Halo 3: ODST and a prequel Halo: Reach in 2009 and 2010 respectively.

Following the release of Halo 3, Bungie announced it was splitting off from Microsoft and becoming an independent limited liability company. While Bungie remained involved in the Halo series by developing games such as ODST and Reach, the rights to Halo remain with Microsoft. To oversee everything Halo, Microsoft created an internal division, 343 Industries,[93] serving as "stewards" for the franchise.[94] Frank O'Connor, formerly a Bungie employee,[95] now serves as 343's creative director.[93]

In announcing the formation of 343 Industries, Microsoft also announced that Xbox Live would be home to a central hub for Halo content called Halo Waypoint.[96] Waypoint is accessed from the Xbox 360 Dashboard and offers players access to multimedia content in addition to tracking their Halo game "career". O'Connor described Waypoint as intended to be the prime destination for Halo.[97]

The company's first new game, Halo 4, was released on November 6, 2012, to generally positive reviews.[98][99]

In 2006, in acknowledgment of the "wealth of influences adopted by the Bungie team", a list of Bungie employees' favorite science fiction material was published on the company's website.[100] The developers acknowledged that the Halo series' use of ring-shaped megastructures followed on from concepts featured in Larry Niven's Ringworld and Iain M. Banks' Culture series (of which Consider Phlebas[101] and Excession[100] were said to be particularly influential). In a retrospective article in Edge, Bungie's Jaime Griesemer commented, "The influence of something like Ringworld isn't necessarily in the design – it's in that feeling of being somewhere else. That sense of scale and an epic story going on out there."[101] Griesemer also explained, "One of the main sources of inspiration was Armor [by John Steakley], in which a soldier has to constantly re-live the same war over and over again. That sense of hopelessness, a relentless battle, was influential."[101] The Flood were influenced by the assimilating alien species in Christopher Rowley's The Vang;[101] it has also been speculated that the Master Chief's name "John 117" may have been a reference to a character named Jon 6725416 in Rowley's Starhammer,[102] or to the John Spartan character of Demolition Man.[103] An IGN article exploring the literary influences present in the Halo franchise commented on similarities between Halo and Orson Scott Card's Ender's Game: aspects of the SPARTAN Project and the design of the Covenant Drones are perceived as reminiscent of the super soldier program and Buggers found in the novel.[102] Bungie has also acknowledged James Cameron's film Aliens as a strong cinematic influence.[104]

A report written by Roger Travis and published by The Escapist compares Halo with the Latin epic Aeneid, written by classical Roman poet Virgil. Travis posits similarities between the plots of both works and compares the characters present in them, with the Flood and Covenant taking the role performed by the Carthaginians, and the Master Chief's role in the series to that of Aeneas.[105]

Seven Halo soundtracks have been released. The Halo Original Soundtrack contains most of Combat Evolved's music. Due to the varying nature of gameplay, the music present was designed to use the game's dynamic audio playback engine. The engine allows for the mood, theme, and duration of music played to change according to gameplay.[106] To afford a more enjoyable listening experience, O'Donnell rearranged portions of the music of Halo into standalone suites, which follow the narrative course of the game. The soundtrack also contains music not used in the game, including a variation on the Halo theme that was first played at Halo's debut at Macworld 1999.[107]

For Halo 2's soundtrack, producer Nile Rodgers and O'Donnell decided to split the music into two separate volumes. The first, Volume One, was released on November 9, 2004 and contained all the themes as well as the "inspired-by" music present in the game (featuring Steve Vai, Incubus, Hoobastank, and Breaking Benjamin). The second release, Volume 2, contained the rest of the music, much of which was incomplete or not included in the first soundtrack, as the first soundtrack was shipped before the game was released.[108]Halo 2, unlike its predecessor, was mixed to take full advantage of Dolby 5.1 Digital Surround Sound.[109]

The soundtrack for Halo 3 was released on November 20, 2007. O'Donnell noted he wanted to bring back the themes from the original game to help tie together the end of the trilogy.[110] The tracks are presented, similarly to the previous soundtrack for Halo 2,[108] in a suite form. Unlike previous soundtracks, where much of the music had been synthesized on computer, the soundtrack for Halo 3 was recorded using a 60-piece orchestra, along with a 24-voice chorus.[111] The final soundtrack was recorded by the Northwest Sinfonia at Studio X in Seattle, Washington.[112] The soundtracks were bundled and released as a box set in December 2008.[113] A soundtrack for Halo 3: ODST was released alongside the game and included many of the tracks from the game.[114]

For Halo Wars, the task of creating the game's music fell to Stephen Rippy. Rippy listened to O'Donnell's soundtracks for inspiration and incorporated the Halo theme into parts of his arrangements. In addition to synthesized and orchestral components, the composer focused on the choir and piano as essential elements, feeling these were important in creating the "Halo sound".[115] Rather than use the Northwest Sinfonia, Rippy traveled to Prague and recorded with the FILMharmonic Orchestra before returning to the United States to complete the music. A standalone compact disc and digital download retail version of the soundtrack was announced in January 2009 for release on February 17.[116]

The Halo franchise includes various types of merchandise and adaptations outside of the video games. This includes bestselling novels, graphic novels, and other licensed products, from action figures to a packaging tie-in with Mountain Dew. Numerous action figures and vehicles based on Halo have been produced. Joyride Studios created Halo and Halo 2 action figures, while Halo 3 poseable and collectible action figures, aimed at collectors, were produced by McFarlane Toys and became some of the top-selling action figures of 2007 and 2008.[117]MEGA Blocks partnered with Microsoft to produce Halo Wars-themed toys.[118]

Numerous printed adaptations based on the Halo video games canon have been published. Larry Niven (author of Ringworld) was originally approached to write a Halo novelization, but declined due to unfamiliarity with the subject matter.[119] The first novel was Halo: The Fall of Reach, a prequel to Halo: Combat Evolved. It was written by Eric Nylund in seven weeks, and published in October 2001.[120]William C. Dietz wrote an adaptation of Halo: Combat Evolved called Halo: The Flood, which was released in 2003.[121] Eric Nylund returned to write the third novel, Halo: First Strike, which takes place between Halo: Combat Evolved and Halo 2, and was published in December 2003. Nylund also wrote the fourth adaptation, Halo: Ghosts of Onyx, which was published on October 31, 2006.[122] Bungie employee Joseph Staten wrote the fifth book, Halo: Contact Harvest, which was released on October 30, 2007, while Tobias S. Buckell produced the sixth, Halo: The Cole Protocol, published in November 2008. Bungie considers the Halo novels as additions to the Halo canon.[123]

A collection of Halo short stories, Halo: Evolutions, was simultaneously released in print and audiobook formats in November 2009. Evolutions includes original material by Nylund, Buckell, Karen Traviss and contributions from Bungie.[124] Tor re-released the first three Halo novels with new content and cover art.[125] Science fiction author Greg Bear wrote a trilogy of books focusing on the Forerunners, called The Forerunner Saga. The first book, entitled Halo: Cryptum, was released in January 2011,[126] followed by Primordium in January 2012 and Silentium on March 19, 2013.[127] Karen Traviss wrote the Kilo-Five trilogy, which takes place after the events of Halo 3 and Halo: Ghosts of Onyx.[128] The first book, Halo: Glasslands, came out October 2011, followed by Halo: The Thursday War on October 2, 2012, and Halo: Mortal Dictata on January 21, 2014. The fourteenth Halo book (the thirteenth novel) was released in November 2014: Halo: Broken Circle by John Shirley, the author of novels based on BioShock, Borderlands, and other games.[129]

Marvel announced at the 2009 Comic Con that two new comics, a five-part series written by Peter David and a second series written by Fred Van Lente, would appear the coming summer and winter.[133] David's series, Halo: Helljumper, is set prior to Halo: Combat Evolved and focuses on the elite Orbital Drop Shock Troopers. The five-part series was published between July and November 2009.[134] Lente's series, originally titled Spartan Black, revolves around a black ops team of Spartan supersoldiers assigned to the UNSC Office of Naval Intelligence.[135] The rebranded comic, Halo: Blood Line, debuted in December 2009.[136] A comic-retelling of the novel Halo: The Fall of Reach was the most recent comic series entitled: Halo: Fall of Reach. Fall of Reach was split into three mini-stories: Boot Camp, Covenant, and Invasion.[137] Two new series were announced in 2013. A three-part series, Halo: Initiation was released August 2013 with Brian Reed returning as writer.[138] Also announced was Halo: Escalation, an ongoing comic series covering the period directly after Halo 4.[139]

In 2005, Columbia Pictures president Peter Schlessel began working outside the studio system to produce a Halo film adaptation. Alex Garland wrote the first script,[140] which was then pitched to studios by couriers dressed as Master Chief. Microsoft's terms required $10 million against 15 percent of gross; most studios passed, citing the lack of risk for Microsoft compared to their large share of potential profits. 20th Century Fox and Universal Studios decided to partner to produce the film, paying Microsoft $5 million to option the film and 10 percent of grosses.[141] Peter Jackson was slated to be the executive producer,[142] with Neill Blomkamp as director. Before Blomkamp signed on, Guillermo del Toro was in negotiations to direct.[143]

D. B. Weiss and Josh Olson rewrote Garland's script during 2006.[144] The crew stopped and resumed preproduction of the film several times.[145] Later that year, 20th Century Fox threatened to pull out of the project, leading Universal to issue an ultimatum to Jackson and Schlessel: either cut their large "first-dollar" deals, or the project was ended. Both refused, and the project stalled.[141]

Blomkamp declared the project dead in late 2007,[146] but Jackson replied that the film would still be made.[147] Blomkamp and Jackson collaborated on District 9, but the director told /Film that he was no longer considering working on a Halo film if the opportunity arose,[148] saying that after working on the film for five months before the project's collapse it would be difficult to return. The rights for the film have since reverted to Microsoft.[149]

Halo 4: Forward Unto Dawn is a live-action film and miniseries set in the Halo universe. Although shot as a feature-length film, Forward Unto Dawn was originally released as a webseries consisting of five roughly 15-minute episodes, the first of which was released on October 5, 2012, with the last episode released on November 2, 2012. The series' plot, occurring in the early days of the Human-Covenant War circa 2526, revolves around Thomas Lasky, a young cadet at Corbulo Academy of Military Science, and how John-117 inspired him to eventually become a leader. Lasky is also a prominent character in Halo 4 as a commander on the UNSC Infinity. The name of the series, aside from being a reference to the UNSC frigate Forward Unto Dawn, is given new significance in the series as part a running motif based on a poem. The film cut was released on Blu-ray and DVD on December 4, 2012.

On April 3, 2014, it was announced that Ridley Scott and his production company, Scott Free Productions, were working on a Halo digital feature alongside 343 Industries and Xbox Entertainment Studios; Scott would be the executive producer, with David W. Zucker and Sergio Mimica-Gezzan as the directors. The feature was expected to follow the same format as Machinima's Halo 4: Forward Unto Dawn.[150] On June 9, 2014, it was announced at E3 2014 that the feature, titled Halo: Nightfall, would be included with Halo: The Master Chief Collection at its November 2014 launch. The feature introduces a new character to the franchise, Agent Jameson Locke, played by actor Mike Colter; Nightfall is considered to be his origin story.[151] Locke is one of the Spartans portrayed on the cover art of Halo 5: Guardians, and is set to play a large role in the series.[152] On July 24, 2014, 343 Industries released the first trailer for the feature.[153]Halo: Nightfall is available to watch through Halo Channel, an application for the Xbox One, Windows 8.1 and Windows Phone.[154] On March 16, 2015, the series became available to stream, download, and buy on physical disc.[155]

On May 21, 2013, 343 Industries announced that a live-action television series of Halo would be produced with Steven Spielberg serving as executive producer. Neill Blomkamp is rumored to direct the pilot for the series.[156] The series will premiere on the American premium cable network Showtime.[157] The project remains in active development as of July, 2016.[158]

Microsoft announced at Comic-Con 2009 that it was overseeing production of a series of seven short anime films, together called Halo Legends. Financed by 343 Industries, the animation was created by five Japanese production houses: Bones, Casio Entertainment, Production I.G., Studio 4°C, and Toei Animation. Shinji Aramaki, creator and director of Appleseed and Appleseed Ex Machina, served as the project's creative director. Warner Bros. distributed Legends on DVD and Blu-ray in February 2010.[93][159] Six of the stories are officially part of the Halo canon, with the seventh, made by Toei, intended to be a parody of the universe.[160] In mid-July 2015, 343 Industries announced that a new animated series of Halo will be included in the Halo 5: Guardians Limited Edition and Collector's Edition called Halo: The Fall of Reach, and will be based on the book Halo: The Fall of Reach by Eric Nylund.[161][162]

The Halo franchise has been highly successful commercially and critically. During the two months following Halo: Combat Evolved's release, it sold alongside more than fifty percent of Xbox consoles[179] and sold a million units by April 2002.[180]Halo 2's sales generated US$125 million on its premiere day, making it the fastest selling United States media product in history up to that time.[181][182] Combined with Halo's sales, the two games sold 14.8 million units before Halo 3's release.[183]

Launch events, such as this one at a Best Buy store in New York City, were held the night of Halo 3's release.

GameSpot reported 4.2 million units of Halo 3 were in retail outlets on September 24, 2007, a day before official release – a world record volume.[184][185]Halo 3 broke the previous record for the highest grossing opening day in entertainment history, making US$170 million in its first twenty-four hours.[7][185] Worldwide, sales exceeded US$300 million the first week, helping to more than double the sales of the Xbox 360 when compared with the weekly average before the Halo 3 launch.[183][186] At the end of 2007, Halo 2 and Halo: Combat Evolved were the number one and two best-selling Xbox titles, respectively, and Halo 3 was the best-selling Xbox 360 title.[187]Halo Wars was the best-selling RTS console game, selling more than one million units.[188] The Halo series went on to sell more than 27 million copies by August 2009,[189] and more than 34 million copies by May 2010.[190][191] Tor Books reported that sales of all franchise materials are greater than $1.7 billion,[125] and Bungie's games before Reach accounted for $1.5 billion in sales.[192] The soundtracks to Halo 2, Halo 3, ODST and Reach all appeared on the Billboard 200 charts for at least one week.[193] By May 2011, total gross of Halo merchandise was $2 billion, with 40 million copies of the games sold.[194] The total amount climbed to $2.3 billion in July 2011,[195] and $2.8 billion in January 2012.[196] Total franchise grosses exceeded $4.6 billion by October 2015, with 25% of the figure from non-game-related merchandise.[197]

The Halo adaptations have been successful as well. Many of the novels have appeared on Publisher Weekly's bestseller charts and the Halo Graphic Novel sold more than 100,000 copies, a "rare hit" for the games-to-comics genre.[198]Ghosts of Onyx, Contact Harvest, The Cole Protocol and the first volume of Cryptum appeared on The New York Times bestseller lists,[121][199][200][201][202][203] and The Cole Protocol also opened 50th overall on USA Today's bestsellers list.[204] Tor's first three novels sold more than one million copies by April 2009.[205]

Overall, the Halo series has been very well received by critics. Halo: Combat Evolved has received numerous Game of the Year awards.[206][207] In March 2007, IGN listed it as the top Xbox game of all time, while readers ranked it the fourteenth best game ever on "IGN Readers' Choice 2006 – The Top 100 Games Ever".[208][209] Conversely, GameSpy ranked Halo: Combat Evolved tenth on its list of "Top 25 Most Overrated Games of All Time", citing repetitive level design and the lack of an online multiplayer mode.[210]Halo 2 also received numerous awards,[211] with IGN listing it as the number two top Xbox game of all time in March 2007.[208] From its initial release on the Xbox in November 2004 until the launch of Gears of War on the Xbox 360 in November 2006 – two years later – Halo 2 was the most popular video game on Xbox Live.[212]Halo 3 was nominated for and won multiple awards; it won Time magazine's "Game of the Year" and IGN chose it as the Best Xbox 360 Online Multiplayer Game and Innovative Design of 2007.[213][214][215] Most publications called the multiplayer aspect one of the best features; IGN said the multiplayer map lineup was the strongest of the series, and GameSpy added that the multiplayer offering will greatly please "Halo veterans".[216][217] Complaints focused on the game's plot. The New York Times said the game had a "throwaway" plot and Total Video Games judged the single-player aspect ultimately disappointing.[218][219] The series' music and audio has received enthusiastic response from game reviewers.[217][220][221]

The main trilogy, particularly its protagonist, has been declared iconic and a symbol of today's videogames; a wax replica of the Master Chief was made by Madame Tussauds in Las Vegas, where Pete Wentz compared the character to notable characters from previous generations like Spider-Man, Frodo, and Luke Skywalker.[222]The Escapist author Roger Travis compared Halo's story to Virgil's Aeneid, saying the religious and political struggle described in the games relates to the modern epic tradition.[105]GamesTM stated Halo: Combat Evolved "changed videogame combat forever", and Halo 2 showcased Xbox Live as a tool for communities.[21] GameDaily noted Halo 2's launch was "easily comparable to the biggest in other sectors of the entertainment industry", marking the first time a video game launch has become a major cultural event in America.[223]Time magazine included the franchise in the "2005 Time 100", highlighting that in the first ten weeks after the release of Halo 2, players spent 91 million combined hours playing the game online.[224] A The New York Times report noted the success of Halo 3 was critical for Microsoft, persuading consumers to buy the Xbox 360 console which was experiencing waning sales compared with the Nintendo Wii, as well as helping restore the console's image. On September 25, 2007, the release date for Halo 3, Microsoft's shares rose 1.7% based on sales expectations for the game.[225]Halo has been described as a series that "has reinvented a genre that didn't know it needed to be reinvented", with aspects of the main trilogy being duplicated in other FPS games multiple times.[226]

As a highly popular video game series with a large and active fan base, the Halo trilogy has given rise to an array of video productions in an emerging entertainment medium, machinima.[228] Virtually all machinima footage based around the Halo games is taken from the multiplayer modes of the main trilogy games. Most productions are set outside Halo canon, while others are based on fan fiction closely relating to the official story. Halo 3 includes a saved film function that allows camera angles not possible in previous games, and other features that simplify production. The game has become one of the most popular tools for generating machinima, and Microsoft updated its user license agreement to allow noncommercial distribution of such films.[229]

^Sones, Benjamin E. (2000-07-14). "Bungie dreams of rings and things, part 2". Computer Games Online. Archived from the original on 2005-04-08. Retrieved 13 April 2013. we don't want people to think this is the game of Niven's Ringworld, simply because it takes place on a ring-shaped artificial world… you'd be surprised how often people assume this. ... structurally it's more similar to the "orbitals" in Iain M. Banks' Culture novels.

^Cuddy, Luke (2011-06-07). Halo and Philosophy: Intellect Evolved. Open Court. ISBN0812697189. [...] Banks put out the Culture series of books, which envisions a slightly smaller structure called an "orbital" -- probably closer to the Halo structures [...]

^Perry, Douglas C. (May 17, 2006). "The Influence of Literature and Myth in Videogames". IGN. Ziff Davis. p. 6. Retrieved August 12, 2007. [Frank O'Connor, Bungie Studios] The idea of a Ringworld, first posited in sci-fi by Larry Niven in his novel of the same name, is actually a variation of a Dyson Sphere, a fantastically impossible object described by the 20th century physicist, Freeman Dyson... icosohedron-shaped artificial worlds have also been used by Iain M. Banks and others because they are cool. And that's why we used one.

^Luke Smith (May 15, 2007). "Finish the Fight on September 25, 2007". Bungie Software. Retrieved May 16, 2007. On September 25, 2007, players will be able to finish the fight they started in Halo: Combat Evolved and continued in Halo 2. Halo 3 will release in Europe on September 26, 2007